21. Sergey Brin

Title: Cofounder and president, Alphabet

Country: US

Age: 42

Along with fellow cofounder Larry Page, Sergey Brin helped orchestrate Google’s massive restructuring, announced in August. The move made Google a subsidiary of a new holding company called Alphabet, run by Brin as president and Page as CEO. All of Google’s other ventures, such as Nest and Google X, are now separate companies under the Alphabet umbrella as well. The tech conglomerate generated $66 billion in sales in 2014. 

The restructuring frees the founding duo from the nitty-gritty details of running the massive company, instead allowing them to focus on exploring inventive new "moon shot" projects and ideas. With top talent and an abundance of resources at their disposal, the company has already made automated homes and self-driving cars a reality. 

Brin, who emigrated from Moscow to the US as a child, connected with Page in 1995 at Stanford, where they were each pursuing a Ph.D. They founded Google three years later, and today Brin and Page have personal fortunes of $38 billion and $42 billion today, respectively.